Hyaluronic acid (average molecular weight: 500,000 to 2,000,000) is a mucopolysaccharide which exists in various tissues (e.g., subcutaneous tissues, eyeballs, and joints) of a living organism. Hyaluronic acid has been widely used as a cosmetic component due to high moisture retention properties (e.g., JP-A-2000-095660). It has been confirmed that oral administration of hyaluronic acid compensates for a decrease in hyaluronic acid content of a living body to improve the moisture retention, elasticity, and flexibility of the skin. Therefore, hyaluronic acid and its salts have been added to various types of food product.
However, since hyaluronic acid is a polysaccharide having a high molecular weight, hyaluronic acid is generally absorbed into a living body to only a small extent. For example, although evaporation of moisture through a skin can be prevented by applying hyaluronic acid, hyaluronic acid permeates the skin tissues to only a small extent and mainly remains on the surface of the skin due to its high molecular weight. Therefore, the skin moisturization effect may be lost if hyaluronic acid is washed away from the surface of the skin due to facial cleansing, bathing, or the like.